#include <iostream>

using namespace std;

class Person {
  public:
    Person(int &age, int height) : age_(age), height_(height) {}
    void setAge(int newAge) const { age_ = newAge; }
    // void setHeight(int newheight) const { height_ = newheight; }
    
    static void printPerson() {
      cout << "This is a person class." << endl;
    }

  private:
    int &age_;
    int height_;
};

int main() {

    int age_m = 20;
    int height_m = 170;
    Person p = Person(age_m, height_m);
    p.setAge(30);
    cout << "age_m = " << age_m << endl;

    auto f = &Person::printPerson;

    return 0;
}